1. Field of the Invention
The present invention relates to a method for adaptively allocating resources of an uplink control channel according to the situation of a system.
2. Discussion of the Related Art
The 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) system includes one or more physical channels and a logical channel mapped to the one or more physical channels. The logical channels are classified into a control channel, a common channel, a dedicated control channel, and a traffic channel, etc. Specifically, an example of the uplink control channel may be a Channel Quality Information CHannel (CQICH).
A conventional method for allocating resources to the uplink control channel is a pre-reserved method. The pre-reserved method estimates the amount of control information to be transmitted to an uplink, pre-reserves the proper amount of uplink resources, and allows a plurality of users to share the corresponding resources.
The pre-reserved method has an advantage in that there is no need to transmit downlink control information capable of transmitting a command associated with a resource allocation method to a mobile station (MS). However, it has difficulty in properly coping with some troublesome situations caused by the insufficient or excessive amount of pre-reserved resources.
In other words, the number of users contained in a coverage of a base station (or Node-B) or the amount of various control information fed back to the uplink may be changed to others according to the situation of a system. The above-mentioned system situation may indicate the number of users of an uplink channel, specific information indicating whether the uplink control channel is used or not, the amount of data or control information transferred via the uplink control channel, the degree of interference, specific information indicating whether a multi-antenna is used, a channel quality information transmission scheme, and a channel situation, etc.
In this case, if the number of users of the uplink channel increases, or the amount of uplink-channel control information increased by the mobile station (MS) based on a multi-antenna scheme is greater than the amount of pre-reserved resources, the pre-reserved method must transmit the uplink-channel control information several times, so that it is unable to implement smooth communication between a transmission end and a reception end. Otherwise, if the small number of users is located in the base station's coverage and the amount of control information to be transferred to the uplink is low, the pre-reserved method has a disadvantage in that it unconditionally allocates all of pre-reserved resources including unnecessary resources not to be used to the users, resulting in the occurrence of wasted resources.